Hook for double stitch sewing machine



June 17, 1958 K. w. HEIMANN ETAL 2,839,019

Hoox FOR DOUBLE STITCH SEWING MACHINE Filed nay 11, 1954 f 2 sheets-sheet 1 /NVENT'OPS June 17, 1958 K. w. HEIMANN ET AL 2,839,019

Hoox FOR DOUBLE STITCH SEWING MACHINE Filed May ll, 1954 2 Sheets-Sheet 2 United States Patent O 2,839,019 HOOK FOR DOUBLE STITCH SEWlNG NIACHINE Karl Wilhelm Heimann and Karl Werle, Kaiserslautern,

Germany, assgnors to G. M. Pfaff A.G., Kaiserslautern, Pfalz, Germany, a corporation of Germany Application May 11, `1954,Serial No. 429,068

Claims priority, application Germany May 13, 1953 8 Claims. (Cl. 11b-228) The invention relates to sewing machines, and relates more particularly to sewing machines of the double stitch type; still more particularly, the invention relates to a rotatable hook for double stitching sewing machines that defines a guide way for the external rib of a xed bobbin case. More particularly still the invention relates to a bow for use in connection with such a hook, and means for maintaining said bow on said hook in active position.

Hooks of this type normally are Iformed of a hub and a body that includes a pointed end for engaging the loop of the upper thread. On the interior of the hook there is formed a guide way that comprises in part an annular groove and a cutaway portion in which there is journalled the external rib of the bobbin case. The cutaway portion is normally covered by a hook bow.

In accordance with the previous constructions, the hook bow is attached to the hook by screw elements. By loosening the bow, there is released about one halt` of the guide way, to remove the bobbin case for cleaning the interior of the hook. In embodiments of the prior art, the bow is either formed as a flat bow or as an angular bow having a rectangular cross section. The use of a at bow requires the use of screws that are mounted parallel to the axis of the hook. This admits none but screws of minute dimensions, unless the diameter of the entire hook is greatly increased.

The angular bow, on the other hand, is held with screws perpendicular to the axis of the hook, and thus permits the use of screws of sufiiciently large size. It provides, however, the drawback that the body of the hook may be deformed during tightening of these screws, which renders such hook incapable of interchange.

In both of the aforementioned constructions of the prior art, there is found the deciency that they are conneeted by means of several screws with attendant loss of time during mounting and dismounting of the bow on the hook.

It is among the principal objects of the invention to provide a hook and bow in which the aforesaid disadvantages are obviated. Broadly speaking, the construction provides for a bow that for a major portion of its length is formed as a attened bow and which is so lformed at its longitudinal ends that it covers the guide way and the wall of the hook body in the manner of an angular bow.

With the above and other objects of the invention in view, the invention consists in the novel constructions, arrangement and combination of various devices, elements and parts, as set forth in the claims hereof, certain embodiments of the same being illustrated in the accompanying drawings and described in the specification.

In the accompanying drawings there are shown perspective views illustrating in:

Fig. l in extended form, a bow in accordance with one embodiment of the invention;

Fig. 2 a spring for use with the embodiment of Fig. l;

Fig. 3 a hook Ifor use in connection with the bow of Fig. 1 and the spring of Fig. 2;

ICC

, 2 Fig. 4 a hook of the type shown in Fig. 3 on which there are attached the bow of Fig. 1 and the spring of i Fig. 2;

Fig. 5 a modied bow seen from the interior;

Fig. 6 the bow of Fig. 5 but seen from the exterior;

Fig. 7 a hook body yfor use with the bow shown in Figs. 5 and 6;

Fig. 8 a still further modified bow seen from the interior;

Fig. 9 the bow of Fig. 8 but seen from the exterior; and

Fig. 10 a hook body for use with the bowv of Figs. 8 and 9.

ln carrying the invention into effect the Aembodiments which have been selected for illustration in the accompanying drawings and for description in this specification and referring now particularly to Figs. l-4 there is provided a hook that includes a hub 1 and a body 2 which includes a point 3. On the interior of the body 2 there is provided a guide way 4 that is formed as an arcuate recess, in one part as a groove adjacent an integral ridge (Fig. 3) and for the remainder as a cutaway portion 5. The cutaway portion 5 is covered by a bow 6 which Aforms a ridge for the recess, and a hinge 7 is provided between the body 2 and the bow 6. A pin 7 forms part of the of screws 13 and 14 that are threaded in screw holes 13 and 14" formed in the wall 15 of the body 2. A rib .16

extends interiorly on the periphery of the top of thel wall 15. The spring 12 has counter-sunk openings 13' and 14' for the passage of the screws 13 and 14.

As best shown in Fig. 4, the bow 6 is hinged with the hinge 7 to the body 2, and its surface 10 of the lug 9 engages the undersurface of the rib 16, while the spring presses against the surface 11 to maintain resiliently the bow 6 in the active position in which it covers the cutaway portion 5 of the guide Way 4. The bow 6 may be moved away from the active position against the power of the spring 12 to permit removal of the bobbin case off the guide way 4 and ont of the hook for cleaning of the hook interior.

The spring 12 is so dimensioned that its active radius is smaller than the radius of the surface 11 about the axis of the hinge pin 7', so that the spring 12 will release the bow 6 following a short outward movement of the bow 6.1'

ln the active position (Fig. 4) the surface 10 engages 1.

the rib 16, which engagement is rendered ineffective when the bow 16 is moved away from the active position.

In the modification, shown in Figs. 5-7, the cutaway portion 5 of the guide way 4 of the body 2 is covered by a bow 17. The bow 17 has at its front end a ilat member 18 and an extension 19 at right angle to the longitudinal direction of the bow 17. The extension 19 has two lateral surfaces that are radially of the axis of the hook. On the rear end of the bow 17 there is provided yan angular piece 22 that has a counter-sunk hole 23 and that has an oblique lateral surface 24. A recess 28 is provided in the wall 25 of the body 2 matching the shape of the extension 19. The wall 25 furthermore has a recess 26 that matches the shape of the piece 22, and includes an oblique surface 27 that matches the surface 24. A depression 29 is provided on top of the wall 25 to receive the member 18.

A screw 23 engages the threaded bore 23" and passes through the bore 23'. and the piece 22 of the recess 26, are so arranged that The extension 19 and recess 20,A

the-bow 17 in the active position is restrained in movernentinY all butV onedirection, andthe screw 23. restrains.

movement in that one direction.

In the modication shown in Figs. 8-10, there is provided' a bow 3.0 that has atthe rearward end' a piece` 30 similar to the piece 22 of the modication of Figs. 5-7', and has at the forward end an extension 31 perpendicular to the longitudinali direction of the flat portion of thebow 30. The flat portion has La l'ower surface 34 (Figs. 8 and 9) for abutment against the top surface of the wall 37 of the body 2. The extension 31 has an oblique side surface 35; and an opposite; surface- 32 that is radial of the axis of the hook, and has Ian inner surface 33. A recess, 36.-. isA provided in the. Wall 37, and the. recess 36 has a shape corresponding to thatY of the extension 31 including an oblique lateral surface corresponding to the surface 35.' The wall 37 has al bore 38" for a screw 38A that passes through a counter-sunk hole 38 that is formedin the piece 30'.

The; oblique surfacel 35 isl so arranged' that the extension 31 widens towards the bottom of the body 2. The extension 31 and the piece 30 and the recess 36 for the extension. 31 of the opposite recess for the piece 30 are so arranged that there is a forced engagement between the bow- 30 and the body` 2 save for movement in one directionA which is restrained by the screws 38.

It will be., apparent to thoseV skilled in the art that the novel' principlesv of the invention disclosed herein in connection with specific exemplications thereof will suggest various other modifications and application of the same. Itl is accordingly desired that in construing the breadth of the appended claims they shall not be limited to the specifcexemplifcationsof the invention described herein.

Having thus described the invention, what we claim as new and desire to be secured` byl Letters Patent, is as follows:

1. In a revoluble hook, for use in connection with a double stitching sewingl machine, in combination, an arcuate Walled body having an internal arcuate recess forming aA guideway and including an integral first ridge alongside a portion of said recess, said walled body being cut away forming an edge near another portion of said recess, andan elongated hook bow removably connected tosaid' body, said hook bow comprising an arc shaped part flattened in a planeperpendicular to the arc and having extensions near the opposite ends, said flattened part of said hook bow defining'a ange projecting inwardlyv over'said edge into the interior of said walled body and forming a second ridge along said other portion of said recess disposed substantially diametricallyf opposite said first ridge, said extensions engaging externally said walled` body.

2. In a hook as claimed in claim 1, together with, hinge means between said body and said hook bow removably connecting said bow to said body, said bow being movable about ther axis of said hinge means to and fromy an active covering position on said body, and

resilient means removably secured to said body pressing saidbow resiliently into4 said activeposition.

3. In a hook as claimed in claim 1, together with, means between said bow and said body releasably engaging said bow on said body restricting movement of said bow in al1 but one direction, and means operable for resisting movement of said hook in said one direction.

4. In` a hook. as claimed in claim 1, said body having external recesses operable each corresponding to the outline and? configurationof an extension for receiving the same, whereby saidY bow will be engaged on said body immovably in all directions but one, and means restraining movement in said one direction.

5. In a hook as claimed in claim 1, one of said extensions of said hook bow being perpendicular to the longitudinal direction thereof, and the other extension having side surfaces disposed radially of the axis of said body, corresponding recesses formed in said body for receiving said extensions in abutment, said' extensions and recesses forming means positioning said hook bow in an active covering'position on' said bodyimmovably in all but one direction, and a screw restraining movement ofk said hook bowr inI said one' direction completing the removable attachment of said hook bowl to said body.

6.1In a hook as claimed in claim l, one of said extensions of said hook bow being perpendicular to the longitudinal direction` thereof, and the other extension having sidesurfacesdi'sposed radially ofthe axis of said body, corresponding recesses formedAv in said body for receiving said extensions in abutment, said extensions and recesses formingv means positioning said hook bow iny anA active covering position on said body immovably in all but one direction, and a screw restraining movement of said hook bow'irrsaid one direction completing the removable attachment of said hook bow-to said body, one of saidside` surfaces being oblique relative to the longitudinal direction' of saidE flattened portion, andthe correspondingV recess' having a matching inclined surface for abutment with said oblique surface.

7l In a hook as claimed in claim 1, said hook bow beinghingedto saidfbod'y, a leaf spring pressing said bow, abutment means intermediate said body and said bow defining anactive covering position of said bow, and resilient means pressing said body into said active position.

8'. In a hook'as claimed in` claim 7, said resilient means including a spring having an active radius smaller than the distance of said abutment; means from the hinge axis.

References Citedin' the ile of this patent UNITED STATES PATENTS 1,008,538 Gray' Nov. 14, 19ll 1,196,940- Finch Sept. 5, 1916 1,431,380 Dickson Oct. 10, 1922 2,009,292V Fleckenstein' July 23, 1935 2,102,954v Hohmann Dec. 21, 1937 

